Forcing Bulbs for Indoor Bloom

'Force' is such a strong word for making a plant bloom out of season. 'Coaxing' is better, maybe even 'teasing', of course, 'fooling' won't do because we all know that Mother Nature will not be made light of. But as long as we understand her rhythms we can speed up the seasons a bit, like nudging spring into our homes during the bleakest of winters. This is especially true, and easy, with bulbs, those remarkable self-contained flower factories.

Choosing Your Bulbs

Most of our common hardy outdoor bulbs are candidates for forcing: Tulips, Crocus, Daffodils, Amaryllis, Paperwhite Narcissus, Muscari, Miniature Iris and Hyacinths. Select only top quality bulbs that are large and heavy for their size and are not soft or moldy. If you're not going to pot right away store them in a mesh onion-like or a ventilated paper bag in your basement or the refrigerator crisper, any place where the temperature stays below 65 degrees and the humidity is fairly high. And this is important: Never refrigerate bulbs with fruit. The ethylene gas produced by ripening fruits destroys the bulb's flowering potential. (By the way, never store them in the freezer.)

It's a Timing Thing

First check your calendar. Most bulbs require 10 to 14 weeks in temperatures below 48 degrees. This is their rooting period and it is absolutely essential if you expect flowers. The actual forcing, 2 to 4 weeks at around 60 degrees, follows the cooling stage.

Potting 'Em Up

Use clean pots with drainage holes. The depth varies according to the size bulb you're forcing. You'll need 2 inches of soil below the bulb in a container large enough for the bulb to be even with the rim when planted. Use a good soilless potting mixture and don't worry about fertilizer, all the bulb requires is contained inside.

Place 2 inches of the mix in the pot, then set your bulbs. Mass them in, even touching each other is fine. Bulbs are very friendly and love a party. But don't combine different kinds of bulbs because they have various cooling requirements.

Finish filling the pot, firming the soil around the bulbs, then water well to settle the soil. And don't forget to include a label with the kind of bulb, the planting date and the day you want to take it out of storage.

Remember that bulbs will flower about 2 to 4 weeks after being brought into warmer temps. So from the actual planting to flowering, ballpark it at 15 weeks.

Place the containers in a refrigerator, a cool spot in the basement, a root cellar (like there are many of those left), a crawl space, cold frame, or better yet, outside if it stays below 45 degrees and does not freeze. Freezing doesn't harm bulbs in the ground, of course, but it will slow down your forcing schedule.

The Forcing

When you take the bulbs out of storage into warmth and light, the growth of leaves and flowers is triggered. First transfer the pots to a place with indirect sunlight and 60 degree temps for a week or two.

When the shoots are 4-6 inches tall, move the pots to a bright, sunny window to stimulate the flowering process. 68 degrees or so and lots of sunshine produce the best flowers. When the buds show color move the pots to indirect light so the flowers last longer. If the flowers are coming on too fast, slow things down by moving the pot out of the light and into a cooler area.

During the forcing, keep the soil moist.

Once a bulb is forced throw it away. It may rebloom but it'll take a couple of years.

And that's it. Pretty easy, huh? All it takes is patience.

The Schedule

This timetable may help you plan but these are only guidelines. Bulbs, like most plants, can't read. In all cases the bulbs must be well rooted before forcing.

To flower in January, plant in September or early October.

Planting in mid-October will produce flowers in February and a late October or early November planting means flowers in late winter.

The Easiest Bulbs to Force

Paperwhite Narcissus is very popular, easy and grows in sand or gravel. They are also available pre-cooled.

Amaryllis are Christmas plants and require no cooling, but plant in early November for holiday flowers.

Crocus will flower after a 12-14 week rooting period and grow in gravel and water.

Hyacinth require only 12 weeks and are easily forced in special 'hyacinth' vases with only water.

Muscari need about 16 weeks and should be jammed together in the pot for the best show.

Iris reticulata are easy, needing about 15 weeks and excellent drainage.

Tulips must have at least 15 weeks. When planting tulips put the flat side facing the pot rim. That way the large outer leaves will drape over the edge and not detract from the flowers.

Daffodils require 12-14 weeks and lots of strong, bright light during forcing. Try the miniature varieties for the best results.

When horticulturist Tom Schneider isn't puttering in his garden he is helping his wife, Deb, with their online machine embroidery design business, Windstar Embroidery. Visit Tom and Deb for embroidered gifts and quality machine embroidery designs.